Circular Polarity

Hi Gang,
Today I bit the bullet and ordered an S-band down converter/preamp
that has really nice specs. That was the easy part. Next I spent a couple
of hours trying to figure out the polarity of the S-band hi-gain antenna on
AO-40 so that I can start shopping for an antenna. I could find no
polarity info for any antenna on AO-40 except the 70 cm arrangement which
is RHCP. I did find an article by G3RUH about how to build an S-band dish
(got that tucked away on the hard drive!) for AO-13, in which he uses a
helix at the feed, wound "opposite to a normal screw thread".
I believe that a signal that leaves the bird from an RHCP antenna
would want to see an LHCP antenna on the ground, unless a dish were in use
which would reverse the polarity on reflection to the focal point. I think...
There must be someone out there who knows the S-band antenna
characteristics for AO-40. Any help directing me toward the path of
righteousness would be appreciated. Especially at these prices!
TNX and 73, Ken
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